Climate related coastal disparity in mangrove resilience in India: ensemble species distribution modelling calls for adaptive conservation.

Mangrove ecosystems are increasingly threatened by climate change and human activities. This study investigates coastal disparities in mangrove habitat suitability and projected species richness along the east and west coasts of India under baseline conditions and future climate scenarios using an ensemble species distribution modelling approach. Eight algorithms were employed to project the distribution of 20 mangrove species under a single baseline scenario and two future climate scenarios (SSP1-2.6 and SSP5-8.5) using the HadGEM model. Future projections were made for four time slices: 2040, 2060, 2080, and 2100. The findings reveal significant variations in the distribution of suitable areas influenced by temperature-related variables and soil characteristics. Under the baseline scenario, the west coast exhibited higher localized species richness, with hotspots identified in the Malabar, Canara, and Konkan coasts. In the east coast, the highly suitable areas are distributed mostly in the Bhāgirathi-Hooghly delta and parts of the Godavari coast. By mid-century (2040-2060), the highly suitable areas in the west coast are predicted to contract by ∼66 % under SSP1-2.6 and by 85-100 % under SSP5-8.5; while in the east coast such areas are predicted to disappear entirely. End-century projections (2080-2100) show that in the west coast, highly suitable areas may disappear completely under SSP5-8.5. The east coast is also expected to lose all highly suitable areas in both scenarios. Only scattered low to moderately suitable tracts are expected to remain around the Sundarbans and lower Mahanadi delta, with most shoreline segments downgrading to low suitability class by 2100. The findings of the study emphasize the urgency of adaptive conservation planning to safeguard the mangrove ecosystems of India and their services in the face of climate change.